Tutorial 18 - GROUP BY And HAVING Clause Video Lecture | Postgresql: A Complete Tutorial - Database Management

hello guys welcome to a post ksq and in
this tutorial I'm going to talk about
the group I and the having clothes so
the group by clause is basically used
for the grouping over data or it
basically combines the columns of our
table which have the same value so this
is very essential in SQL when you want
to achieve grouping in our data for
example I want to know all the employees
in my company that have an age of 34 or
who have an salary of 2,000 or who live
in Kolkata who live in New Delhi so live
in any place so for this I will use
group by it will group all the employees
before a particular result like suppose
I want to check that how many employees
of which age group exist in my company
so for that I will use the group by
clause that is select age select age and
then count count star boundary distinct
from company group by age now here I
will I'm grouping by 8 so means that the
fields will be grouped by age the
similar age fields will be grouped
together I will see the results that is
you can see that I have one employee
oops I have one employee whose age is 40
I have three employees who they just
study for one for 35 and respectively I
have one for each and every age group so
this is the usage of the group by clause
so as you can see the group by basically
groups the data now suppose I want to
check for the employees of different
states or for which place they belong to
I will run the following very select
address group by address so now you
would be able to see that I have one
employee in Chennai I have to employ one
employee in Bengaluru two in Kolkata and
you can see respectively I have two
employees and two in Mumbai and two in
Delhi so this is the use of the group by
clause now with this we could have the
having
having clothes is just remember having
clothes cannot be inserted or cannot be
achieved by without group by clause so
to run a having clothes we need to have
an group by clause so it is a compulsion
and moreover having clause is only run
on aggregate operators that is the
minimum maximum and the some operator so
these operators are basically used to
run the hanging operator having operator
is not normal operator and it is not run
by the normal expressions so you need to
have an aggregate operator for having
and you need to have a group Group group
by clause to run or having clause so you
can see that I will have having maximum
salary greater than 2000 so you will see
that it runs now so you could see this
whose salary is greater than 2000
maximum side is greater than 2000 I get
those results so this is a user having
loss so thank you for install subscribe
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